Automated methods of conducting microscopic analysis of biological samples enhance diagnostic procedures and optimize the throughput of samples in a microscope-based diagnostic facility. Various co-owned U.S. patent applications, described more fully below, disclose aspects and embodiments of apparatuses and methods for automated microscopic analysis. These include an integrated robotic microscope system, a dynamic automated microscope operation and slide scanning system, various interchangeable objective lenses, filters, and similar elements for use in an automated microscope system, an automated microscope stage for use in an automated microscope system, an automated microscope slide cassette and slide handling system for use in an automated microscope system, an automated microscope slide loading and unloading mechanism for use in an automated microscope system, automated methods that employ computer-resident programs to drive the microscopic detection of fluorescent signals from a biological sample, useable to drive an automated microscope system, and automatic operation of a microscope using computer-resident programs to drive the microscope in conducting a FISH assay for image processing.
A method of scanning and analysis of cytology and histology samples using a flatbed scanner to capture images of the structures of interest for the analysis of common pathology staining techniques is disclosed in U.S. Pat. No. 7,133,543 issued Nov. 7, 2006.
A commonly studied mechanism for gene overexpression in cancer cells is generally referred to as gene amplification. This is a process whereby a gene is duplicated within the chromosomes of an ancestral cell into multiple copies. The process involves unscheduled replications of the region of the chromosome comprising the gene, followed by recombination of the replicated segments back into the chromosome (Alitalo K. et al. (1986), Adv. Cancer Res. 47:235-281). As a result, 50 or more copies of the gene may be produced. The duplicated region is sometimes referred to as an “amplicon”. The level of expression of the gene (that is, the amount of messenger RNA produced) escalates in the transformed cell in the same proportion as the number of copies of the gene that are made (Alitalo et al.).
Several human oncogenes have been described, some of which are amplified in a significant proportion of breast tumors. A prototype is the erbB2 gene (also known as HER-2/neu), which encodes a 185 kDa membrane growth factor receptor homologous to the epidermal growth factor receptor. erbB2 is amplified in 61 of 283 tumors (22%) tested in a recent survey (Adnane J. et al. (1991), Oncogene 6:659-661). Other oncogenes amplified in breast cancer are the bek gene, duplicated in 34 out of 286 (12%); the flg gene, amplified in 37 out of 297 (12%); and the myc gene, amplified in 43 out of 275 (16%) (Adnane et al.).
Work with other oncogenes, particularly those described for neuroblastoma, suggests that gene duplication of the proto-oncogene is an event involved in the more malignant forms of cancer, and could act as a predictor of clinical outcome (reviewed by Schwab M. et a). (1990), Genes Chromosomes Cancer 1:181-193; and Alitalo et al.). In breast cancer, duplication of the erbB2 gene has been reported as correlating both with reoccurrence of the disease and decreased survival times (Slamon D. J. et al. (1987), Science 235:178-182). There is some evidence that erbB2 helps identify tumors that are responsive to adjuvant chemotherapy with cyclophosphamide, doxorubicin, and fluorouracil (Muss et al.).
Only a proportion of the genes that can undergo gene duplication in breast cancer have been identified. First, chromosome abnormalities, such as double minute (DM) chromosomes and homogeneously stained regions (HSRs), are abundant in cancer cells. HSRs are chromosomal regions that appear in karyotype analysis with intermediate density Giemsa staining throughout their length, rather than with the normal pattern of alternating dark and light bands. They correspond to multiple gene repeats. HSRs are particularly abundant in breast cancers, showing up in 60-65% of tumors surveyed (Dutrillaux B. et al. (1990), Cancer Genet Cytogenet 49:203-217; Zafrani B. et al. (1992), Hum Pathol 23:542-547). When such regions are checked by in situ hybridization with probes for any of 16 known human oncogenes, including erbB2 and myc, only a proportion of tumors show any hybridization to HSR regions. Furthermore, only a proportion of the HSRs within each karyotype are implicated.
Second, comparative genomic hybridization (CGH) has revealed the presence of copy number increases in tumors, even in chromosomal regions outside of HSRs. CGH is a new method in which whole chromosome spreads are stained simultaneously with DNA fragments from normal cells and from cancer cells, using two different fluorochromes. The images are computer-processed for the fluorescence ratio, revealing chromosomal regions that have undergone amplification or deletion in the cancer cells (Kallioniemi A. et al. (1992), Science 258:818-821). This method was recently applied to 15 breast cancer cell lines (Kallioniemi A. et al. (1994), Proc. Natl. Acad. Sci. USA 91:2156-2160). DNA sequence copy number increases were detected in all 23 chromosome pairs.
So, C-K, et al. (Clinical Cancer Research 10: 19-27, 2004) found internal tandem duplication of cyclic AMP response element binding protein (CBP), a nuclear transcriptional coactivator protein, in esophageal squamous cell carcinoma samples from Linzhou (Linxian), China. So et al. show internal tandem duplication of the CBP gene is a frequent genetic event in human squamous cell carcinoma.
The human epidermal growth factor receptor 2 (HER-2)/neu c-erbB-2) gene is localized to chromosome 17q and encodes a transmembrane tyrosine kinase receptor protein that is a member of the epidermal growth factor receptor (EGFR) or HER family (Ross, J S, et al., The Oncologist, Vol. 8, No. 4, 307-325, August 2003). The HER-2 gene is amplified in a fraction, perhaps 25%, of human breast cancers.
Fluorescence in situ hybridization (FISH) is commonly used for the detection of chromosomal abnormalities including aneuploidy screening or chromosomal translocations.
As commonly performed in the field, analysis of FISH labeling of biological samples is laborious and time-consuming, involving the intense efforts of a pathologist and others in the preparation and scrutiny of slides bearing the FISH probes. In addition, the FISH probes themselves are costly, which contributes significantly to carrying out an assay.
Thus there remains a need in the field for minimizing human intervention in conducting FISH assays. There further is a need, currently not met, for the automated collection and analysis of images arising from cancer tissue samples treated with FISH probes. Still further there is a strong need to minimize the quantity of a FISH probe that needs to be used, in order to reduce expenses. Additionally there remains a need for convenient, rapid, hands-free automated fluorescence microscopy of such FISH-probed samples.